Markup Languages have attained wide popularity in recent years. One type of markup language, Extensible Markup Language (XML), is a universal language that provides a way to identify, exchange, and process various kinds of data. For example, XML is used to create documents that can be utilized by a variety of application programs. Elements of an XML file have an associated namespace and schema.
In XML, a namespace is a unique identifier for a collection of names that are used in XML documents as element types and attribute names. The name of a namespace is commonly used to uniquely identify each class of an XML document. The unique namespaces differentiate markup elements that come from different sources and happen to have the same name.
XML Schemata provide a way to describe and validate data in an XML environment. A schema states what elements and attributes are used to describe content in an XML document, where each element is allowed, what types of text contents are allowed within it and which elements can appear within which other elements. The use of schemata ensures that the document is structured in a consistent manner. Schemata may be created by a user and generally supported by an associated markup language, such as XML. By using an XML editor, the user can manipulate the XML file and generate XML documents that adhere to the schema the user has created. XML documents may be created to adhere to one or more schemata.
The XML standard is considered by many to be the ASCII format of the future, due to its expected pervasiveness throughout the hi-tech industry in the coming years. Recently, some word-processors have begun producing documents that are somewhat XML compatible. For example, some documents may be parsed using an application that understands XML.
Another type of markup language is considered an extension of XML is Extensible Application Markup Language (XAML). XAML is often used to produce documents with relation to the document's user interface.
Developers have traditionally used imperative programming for developing software, rather than a declarative definition of a hierarchy of objects. A markup definition of a hierarchy of objects is commonly specified with properties and events wired to programmatic code, which raises the level of abstraction for developers. What is needed is a new type of file that can describe the definition of the hierarchy of objects in a readable format.